Feature: Configuration file parsing

- Add support for parsing configuration files using libconfig.
  (Dependency on libconfig could be made optional once we get some
  better building system.) Few tests has been done, bugs to be expected.
  compton searches for a configuration file mostly according to the XDG
  standard. Firstly the configuration file requested by --config, then
  $XDG_CONFIG_HOME/compton.conf (~/.config/compton.conf, usually), then
  ~/.compton.conf, then compton.conf under $XDG_DATA_DIRS (often
  /etc/xdg/compton.conf). A sample configuration file is supplied as
  compton.sample.conf. Configuration file syntax may change in the
  future.  Commandline switches has higher priority than configuration
  file, except for --shadow-exclude. Use --config /dev/null to
  temporarily disable configuration file.

- Fix a bug that causes windows to disappear or be partially rendered on
  opacity changes.

- Fix a bug that causes some windows to ignore -i (inactive_opacity) and
  --inactive-dim, caused by the default window type change in
  a5d9955ca4.

2 files changed, 460 insertions, 133 deletions

diff --git a/compton.c b/compton.c
index 8945c7749..519c8ca1a 100644
--- a/compton.c
+++ b/compton.c
@@ -87,10 +87,6 @@ Bool win_type_fade[NUM_WINTYPES];
  * Macros
  */
 
-#define IS_NORMAL_WIN(w) \
-((w) && ((w)->window_type == WINTYPE_NORMAL \
-         || (w)->window_type == WINTYPE_UTILITY))
-
 #define HAS_FRAME_OPACITY(w) \
   (frame_opacity && (w)->top_width)
 
@@ -98,6 +94,7 @@ Bool win_type_fade[NUM_WINTYPES];
  * Options
  */
 
+char *display = NULL;
 int shadow_radius = 12;
 int shadow_offset_x = -15;
 int shadow_offset_y = -15;
@@ -137,8 +134,20 @@ wincond *shadow_blacklist = NULL;
 /// Fading blacklist. A linked list of conditions.
 wincond *fade_blacklist = NULL;
 
+/// Whether to fork to background.
+Bool fork_after_register = False;
+/// Red, green and blue tone of the shadow.
+double shadow_red = 0.0, shadow_green = 0.0, shadow_blue = 0.0;
+
 Bool synchronize = False;
 
+// Temporary options
+Bool shadow_enable = False;
+Bool fading_enable = False;
+Bool no_dock_shadow = False;
+Bool no_dnd_shadow = False;
+double menu_opacity = 1.0;
+
 /**
  * Fades
  */
@@ -740,6 +749,9 @@ win_match(win *w, wincond *condlst, wincond **cache) {
  */
 static Bool
 condlst_add(wincond **pcondlst, const char *pattern) {
+  if (!pattern)
+    return False;
+
   unsigned plen = strlen(pattern);
   wincond *cond;
   const char *pos;
@@ -1231,6 +1243,10 @@ paint_preprocess(Display *dpy, win *list) {
 
     if (!w->extents) {
       w->extents = win_extents(dpy, w);
+      // If w->extents does not exist, the previous add_damage_win()
+      // call when opacity changes has no effect, so redo it here.
+      if (w->opacity != opacity_old)
+        add_damage_win(dpy, w);
     }
 
     // Rebuild alpha_pict only if necessary
@@ -1765,8 +1781,6 @@ determine_mode(Display *dpy, win *w) {
   }
 
   w->mode = mode;
-
-  add_damage_win(dpy, w);
 }
 
 /**
@@ -1811,7 +1825,7 @@ calc_opacity(Display *dpy, win *w, Bool refetch_prop) {
   }
 
   // Respect inactive_opacity in some cases
-  if (inactive_opacity && IS_NORMAL_WIN(w) && False == w->focused
+  if (inactive_opacity && is_normal_win(w) && False == w->focused
       && (OPAQUE == opacity || inactive_opacity_override)) {
     opacity = inactive_opacity;
   }
@@ -1823,7 +1837,7 @@ static void
 calc_dim(Display *dpy, win *w) {
   Bool dim;
 
-  if (inactive_dim && IS_NORMAL_WIN(w) && !(w->focused)) {
+  if (inactive_dim && is_normal_win(w) && !(w->focused)) {
     dim = True;
   } else {
     dim = False;
@@ -2916,6 +2930,8 @@ usage(void) {
     "  Daemonize process.\n"
     "-S\n"
     "  Enable synchronous operation (for debugging).\n"
+    "--config path\n"
+    "  Look for configuration file at the path.\n"
     "--shadow-red value\n"
     "  Red color value of shadow (0.0 - 1.0, defaults to 0).\n"
     "--shadow-green value\n"
@@ -3005,87 +3021,229 @@ fork_after(void) {
   freopen("/dev/null", "w", stderr);
 }
 
+#ifdef CONFIG_LIBCONFIG
+/**
+ * Get a file stream of the configuration file to read.
+ *
+ * Follows the XDG specification to search for the configuration file.
+ */
+static FILE *
+open_config_file(char *cpath, char **ppath) {
+  const static char *config_filename = "/compton.conf";
+  const static char *config_filename_legacy = "/.compton.conf";
+  const static char *config_home_suffix = "/.config";
+  const static char *config_system_dir = "/etc/xdg";
+
+  char *dir = NULL, *home = NULL;
+  char *path = cpath;
+  FILE *f = NULL;
+
+  if (path) {
+    f = fopen(path, "r");
+    if (f && ppath)
+      *ppath = path;
+    else
+      free(path);
+    return f;
+  }
+
+  // Check user configuration file in $XDG_CONFIG_HOME firstly
+  if (!((dir = getenv("XDG_CONFIG_HOME")) && strlen(dir))) {
+    if (!((home = getenv("HOME")) && strlen(home)))
+      return NULL;
+
+    path = mstrjoin3(home, config_home_suffix, config_filename);
+  }
+  else
+    path = mstrjoin(dir, config_filename);
+
+  f = fopen(path, "r");
+
+  if (f && ppath)
+    *ppath = path;
+  else
+    free(path);
+  if (f)
+    return f;
+
+  // Then check user configuration file in $HOME
+  if ((home = getenv("HOME")) && strlen(home)) {
+    path = mstrjoin(home, config_filename_legacy);
+    f = fopen(path, "r");
+    if (f && ppath)
+      *ppath = path;
+    else
+      free(path);
+    if (f)
+      return f;
+  }
+
+  // Check system configuration file in $XDG_CONFIG_DIRS at last
+  if ((dir = getenv("XDG_CONFIG_DIRS")) && strlen(dir)) {
+    char *part = strtok(dir, ":");
+    while (part) {
+      path = mstrjoin(part, config_filename);
+      f = fopen(path, "r");
+      if (f && ppath)
+        *ppath = path;
+      else
+        free(path);
+      if (f)
+        return f;
+      part = strtok(NULL, ":");
+    }
+  }
+  else {
+    path = mstrjoin(config_system_dir, config_filename);
+    f = fopen(path, "r");
+    if (f && ppath)
+      *ppath = path;
+    else
+      free(path);
+    if (f)
+      return f;
+  }
+
+  return NULL;
+}
+
+/**
+ * Parse a configuration file from default location.
+ */
 static void
-get_atoms(void) {
-  extents_atom = XInternAtom(dpy, "_NET_FRAME_EXTENTS", False);
-  opacity_atom = XInternAtom(dpy, "_NET_WM_WINDOW_OPACITY", False);
-  frame_extents_atom = XInternAtom(dpy, "_NET_FRAME_EXTENTS", False);
-  client_atom = XA_WM_CLASS;
-  name_atom = XA_WM_NAME;
-  name_ewmh_atom = XInternAtom(dpy, "_NET_WM_NAME", False);
-  class_atom = XA_WM_CLASS;
+parse_config(char *cpath) {
+  char *path = NULL, *parent = NULL;
+  FILE *f;
+  config_t cfg;
+  int ival = 0;
+  double dval = 0.0;
+
+  f = open_config_file(cpath, &path);
+  if (!f) {
+    if (cpath)
+      printf("Failed to read the specified configuration file.\n");
+    return;
+  }
 
-  win_type_atom = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE", False);
-  win_type[WINTYPE_UNKNOWN] = 0;
-  win_type[WINTYPE_DESKTOP] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_DESKTOP", False);
-  win_type[WINTYPE_DOCK] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_DOCK", False);
-  win_type[WINTYPE_TOOLBAR] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_TOOLBAR", False);
-  win_type[WINTYPE_MENU] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_MENU", False);
-  win_type[WINTYPE_UTILITY] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_UTILITY", False);
-  win_type[WINTYPE_SPLASH] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_SPLASH", False);
-  win_type[WINTYPE_DIALOG] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_DIALOG", False);
-  win_type[WINTYPE_NORMAL] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_NORMAL", False);
-  win_type[WINTYPE_DROPDOWN_MENU] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_DROPDOWN_MENU", False);
-  win_type[WINTYPE_POPUP_MENU] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_POPUP_MENU", False);
-  win_type[WINTYPE_TOOLTIP] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_TOOLTIP", False);
-  win_type[WINTYPE_NOTIFY] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_NOTIFICATION", False);
-  win_type[WINTYPE_COMBO] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_COMBO", False);
-  win_type[WINTYPE_DND] = XInternAtom(dpy,
-    "_NET_WM_WINDOW_TYPE_DND", False);
+  config_init(&cfg);
+  parent = dirname(path);
+  if (parent)
+    config_set_include_dir(&cfg, parent);
+
+  if (CONFIG_FALSE == config_read(&cfg, f)) {
+    printf("Error when reading configuration file \"%s\", line %d: %s\n",
+        path, config_error_line(&cfg), config_error_text(&cfg));
+    config_destroy(&cfg);
+    free(path);
+    return;
+  }
+  config_set_auto_convert(&cfg, 1);
+
+  free(path);
+
+  // Get options from the configuration file. We don't do range checking
+  // right now. It will be done later
+
+  // -D (fade_delta)
+  if (config_lookup_int(&cfg, "fade-delta", &ival))
+    fade_delta = ival;
+  // -I (fade_in_step)
+  if (config_lookup_float(&cfg, "fade-in-step", &dval))
+    fade_in_step = normalize_d(dval) * OPAQUE;
+  // -O (fade_out_step)
+  if (config_lookup_float(&cfg, "fade-out-step", &dval))
+    fade_out_step = normalize_d(dval) * OPAQUE;
+  // -r (shadow_radius)
+  config_lookup_int(&cfg, "shadow-radius", &shadow_radius);
+  // -o (shadow_opacity)
+  config_lookup_float(&cfg, "shadow-opacity", &shadow_opacity);
+  // -l (shadow_offset_x)
+  config_lookup_int(&cfg, "shadow-offset-x", &shadow_offset_x);
+  // -t (shadow_offset_y)
+  config_lookup_int(&cfg, "shadow-offset-y", &shadow_offset_y);
+  // -i (inactive_opacity)
+  if (config_lookup_float(&cfg, "inactive-opacity", &dval))
+    inactive_opacity = normalize_d(dval) * OPAQUE;
+  // -e (frame_opacity)
+  config_lookup_float(&cfg, "frame-opacity", &frame_opacity);
+  // -z (clear_shadow)
+  if (config_lookup_bool(&cfg, "clear-shadow", &ival))
+    clear_shadow = ival;
+  // -c (shadow_enable)
+  if (config_lookup_bool(&cfg, "shadow", &ival))
+    shadow_enable = ival;
+  // -C (no_dock_shadow)
+  if (config_lookup_bool(&cfg, "no-dock-shadow", &ival))
+    no_dock_shadow = ival;
+  // -G (no_dnd_shadow)
+  if (config_lookup_bool(&cfg, "no-dnd-shadow", &ival))
+    no_dnd_shadow = ival;
+  // -m (menu_opacity)
+  config_lookup_float(&cfg, "menu-opacity", &menu_opacity);
+  // -f (fading_enable)
+  if (config_lookup_bool(&cfg, "fading", &ival))
+    fading_enable = ival;
+  // --shadow-red
+  config_lookup_float(&cfg, "shadow-red", &shadow_red);
+  // --shadow-green
+  config_lookup_float(&cfg, "shadow-green", &shadow_green);
+  // --shadow-blue
+  config_lookup_float(&cfg, "shadow-blue", &shadow_blue);
+  // --inactive-opacity-override
+  if (config_lookup_bool(&cfg, "inactive-opacity-override", &ival))
+    inactive_opacity_override = ival;
+  // --inactive-dim
+  config_lookup_float(&cfg, "inactive-dim", &inactive_dim);
+  // --mark-wmwin-focused
+  if (config_lookup_bool(&cfg, "mark-wmwin-focused", &ival))
+    mark_wmwin_focused = ival;
+  // --shadow-exclude
+  {
+    config_setting_t *shadow_blacklist_setting =
+      config_lookup(&cfg, "shadow-exclude");
+    if (shadow_blacklist_setting) {
+      // Parse an array of shadow-exclude
+      if (config_setting_is_array(shadow_blacklist_setting)) {
+        int i = config_setting_length(shadow_blacklist_setting);
+        while (i--) {
+          condlst_add(&shadow_blacklist,
+              config_setting_get_string_elem(shadow_blacklist_setting, i));
+        }
+      }
+      // Treat it as a single pattern if it's a string
+      else if (CONFIG_TYPE_STRING ==
+          config_setting_type(shadow_blacklist_setting)) {
+        condlst_add(&shadow_blacklist,
+            config_setting_get_string(shadow_blacklist_setting));
+      }
+    }
+  }
+
+  config_destroy(&cfg);
 }
+#endif
 
-int
-main(int argc, char **argv) {
-  const static struct option longopt[] = {
-    { "shadow-red", required_argument, NULL, 0 },
-    { "shadow-green", required_argument, NULL, 0 },
-    { "shadow-blue", required_argument, NULL, 0 },
-    { "inactive-opacity-override", no_argument, NULL, 0 },
-    { "inactive-dim", required_argument, NULL, 0 },
-    { "mark-wmwin-focused", no_argument, NULL, 0 },
-    { "shadow-exclude", required_argument, NULL, 0 },
+/**
+ * Process arguments and configuration files.
+ */
+static void
+get_cfg(int argc, char *const *argv) {
+  const static char *shortopts = "D:I:O:d:r:o:m:l:t:i:e:scnfFCaSzGb";
+  const static struct option longopts[] = {
+    { "config", required_argument, NULL, 256 },
+    { "shadow-red", required_argument, NULL, 257 },
+    { "shadow-green", required_argument, NULL, 258 },
+    { "shadow-blue", required_argument, NULL, 259 },
+    { "inactive-opacity-override", no_argument, NULL, 260 },
+    { "inactive-dim", required_argument, NULL, 261 },
+    { "mark-wmwin-focused", no_argument, NULL, 262 },
+    { "shadow-exclude", required_argument, NULL, 263 },
     // Must terminate with a NULL entry
     { NULL, 0, NULL, 0 },
   };
 
-  XEvent ev;
-  Window root_return, parent_return;
-  Window *children;
-  unsigned int nchildren;
-  int i;
-  XRenderPictureAttributes pa;
-  struct pollfd ufd;
-  int composite_major, composite_minor;
-  char *display = 0;
-  int o;
-  int longopt_idx;
-  Bool no_dock_shadow = False;
-  Bool no_dnd_shadow  = False;
-  Bool fork_after_register = False;
-  double shadow_red = 0.0;
-  double shadow_green = 0.0;
-  double shadow_blue = 0.0;
-  win *t;
-
-  gettimeofday(&time_start, NULL);
-
-  // Set locale so window names with special characters are interpreted
-  // correctly
-  setlocale (LC_ALL, "");
+  int o, longopt_idx, i;
+  char *config_file = NULL;
 
   for (i = 0; i < NUM_WINTYPES; ++i) {
     win_type_fade[i] = False;
@@ -3093,45 +3251,31 @@ main(int argc, char **argv) {
     win_type_opacity[i] = 1.0;
   }
 
-  while ((o = getopt_long(argc, argv,
-          "D:I:O:d:r:o:m:l:t:i:e:scnfFCaSzGb",
-          longopt, &longopt_idx)) != -1) {
+  // Pre-parse the commandline arguments to check for --config and invalid
+  // switches
+  while (-1 !=
+      (o = getopt_long(argc, argv, shortopts, longopts, &longopt_idx))) {
+    if (256 == o)
+      config_file = mstrcpy(optarg);
+    else if ('?' == o || ':' == o)
+      usage();
+  }
+
+#ifdef CONFIG_LIBCONFIG
+  parse_config(config_file);
+#endif
+
+  // Parse commandline arguments. Range checking will be done later.
+  optind = 1;
+  while (-1 !=
+      (o = getopt_long(argc, argv, shortopts, longopts, &longopt_idx))) {
     switch (o) {
-      // Long options
-      case 0:
-        switch (longopt_idx) {
-          case 0:
-            shadow_red = normalize_d(atof(optarg));
-            break;
-          case 1:
-            shadow_green = normalize_d(atof(optarg));
-            break;
-          case 2:
-            shadow_blue = normalize_d(atof(optarg));
-            break;
-          case 3:
-            inactive_opacity_override = True;
-            break;
-          case 4:
-            inactive_dim = normalize_d(atof(optarg));
-            break;
-          case 5:
-            mark_wmwin_focused = True;
-            break;
-          case 6:
-            condlst_add(&shadow_blacklist, optarg);
-            break;
-        }
-        break;
       // Short options
       case 'd':
         display = optarg;
         break;
       case 'D':
         fade_delta = atoi(optarg);
-        if (fade_delta < 1) {
-          fade_delta = 10;
-        }
         break;
       case 'I':
         fade_in_step = normalize_d(atof(optarg)) * OPAQUE;
@@ -3140,22 +3284,16 @@ main(int argc, char **argv) {
         fade_out_step = normalize_d(atof(optarg)) * OPAQUE;
         break;
       case 'c':
-        for (i = 0; i < NUM_WINTYPES; ++i) {
-          win_type_shadow[i] = True;
-        }
-        win_type_shadow[WINTYPE_DESKTOP] = False;
+        shadow_enable = True;
         break;
       case 'C':
         no_dock_shadow = True;
         break;
       case 'm':
-        win_type_opacity[WINTYPE_DROPDOWN_MENU] = atof(optarg);
-        win_type_opacity[WINTYPE_POPUP_MENU] = atof(optarg);
+        menu_opacity = atof(optarg);
         break;
       case 'f':
-        for (i = 0; i < NUM_WINTYPES; ++i) {
-          win_type_fade[i] = True;
-        }
+        fading_enable = True;
         break;
       case 'F':
         fade_trans = True;
@@ -3167,7 +3305,7 @@ main(int argc, char **argv) {
         shadow_radius = atoi(optarg);
         break;
       case 'o':
-        shadow_opacity = normalize_d(atof(optarg));
+        shadow_opacity = atof(optarg);
         break;
       case 'l':
         shadow_offset_x = atoi(optarg);
@@ -3177,12 +3315,9 @@ main(int argc, char **argv) {
         break;
       case 'i':
         inactive_opacity = (normalize_d(atof(optarg)) * OPAQUE);
-        if (OPAQUE == inactive_opacity) {
-          inactive_opacity = 0;
-        }
         break;
       case 'e':
-        frame_opacity = normalize_d(atof(optarg));
+        frame_opacity = atof(optarg);
         break;
       case 'z':
         clear_shadow = True;
@@ -3199,20 +3334,79 @@ main(int argc, char **argv) {
       case 'b':
         fork_after_register = True;
         break;
+      // Long options
+      case 256:
+        // --config
+        break;
+      case 257:
+        // --shadow-red
+        shadow_red = atof(optarg);
+        break;
+      case 258:
+        // --shadow-green
+        shadow_green = atof(optarg);
+        break;
+      case 259:
+        // --shadow-blue
+        shadow_blue = atof(optarg);
+        break;
+      case 260:
+        // --inactive-opacity-override
+        inactive_opacity_override = True;
+        break;
+      case 261:
+        // --inactive-dim
+        inactive_dim = atof(optarg);
+        break;
+      case 262:
+        // --mark-wmwin-focused
+        mark_wmwin_focused = True;
+        break;
+      case 263:
+        // --shadow-exclude
+        condlst_add(&shadow_blacklist, optarg);
+        break;
       default:
         usage();
         break;
     }
   }
 
-  if (no_dock_shadow) {
-    win_type_shadow[WINTYPE_DOCK] = False;
+  // Range checking and option assignments
+  fade_delta = max_i(fade_delta, 1);
+  shadow_radius = max_i(shadow_radius, 1);
+  shadow_red = normalize_d(shadow_red);
+  shadow_green = normalize_d(shadow_green);
+  shadow_blue = normalize_d(shadow_blue);
+  inactive_dim = normalize_d(inactive_dim);
+  frame_opacity = normalize_d(frame_opacity);
+  shadow_opacity = normalize_d(shadow_opacity);
+  menu_opacity = normalize_d(menu_opacity);
+  if (OPAQUE == inactive_opacity) {
+    inactive_opacity = 0;
+  }
+  if (shadow_enable) {
+    for (i = 0; i < NUM_WINTYPES; ++i) {
+      win_type_shadow[i] = True;
+    }
+    win_type_shadow[WINTYPE_DESKTOP] = False;
+    if (no_dock_shadow)
+      win_type_shadow[WINTYPE_DOCK] = False;
+    if (no_dnd_shadow)
+      win_type_shadow[WINTYPE_DND] = False;
+  }
+  if (fading_enable) {
+    for (i = 0; i < NUM_WINTYPES; ++i) {
+      win_type_fade[i] = True;
+    }
   }
-
-  if (no_dnd_shadow) {
-    win_type_shadow[WINTYPE_DND] = False;
+  if (1.0 != menu_opacity) {
+    win_type_opacity[WINTYPE_DROPDOWN_MENU] = menu_opacity;
+    win_type_opacity[WINTYPE_POPUP_MENU] = menu_opacity;
   }
 
+  // Other variables determined by options
+
   // Determine whether we need to track focus changes
   if (inactive_opacity || inactive_dim) {
     track_focus = True;
@@ -3221,6 +3415,70 @@ main(int argc, char **argv) {
   // Determine whether we need to track window name and class
   if (shadow_blacklist || fade_blacklist)
     track_wdata = True;
+}
+
+static void
+get_atoms(void) {
+  extents_atom = XInternAtom(dpy, "_NET_FRAME_EXTENTS", False);
+  opacity_atom = XInternAtom(dpy, "_NET_WM_WINDOW_OPACITY", False);
+  frame_extents_atom = XInternAtom(dpy, "_NET_FRAME_EXTENTS", False);
+  client_atom = XA_WM_CLASS;
+  name_atom = XA_WM_NAME;
+  name_ewmh_atom = XInternAtom(dpy, "_NET_WM_NAME", False);
+  class_atom = XA_WM_CLASS;
+
+  win_type_atom = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE", False);
+  win_type[WINTYPE_UNKNOWN] = 0;
+  win_type[WINTYPE_DESKTOP] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_DESKTOP", False);
+  win_type[WINTYPE_DOCK] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_DOCK", False);
+  win_type[WINTYPE_TOOLBAR] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_TOOLBAR", False);
+  win_type[WINTYPE_MENU] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_MENU", False);
+  win_type[WINTYPE_UTILITY] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_UTILITY", False);
+  win_type[WINTYPE_SPLASH] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_SPLASH", False);
+  win_type[WINTYPE_DIALOG] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_DIALOG", False);
+  win_type[WINTYPE_NORMAL] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_NORMAL", False);
+  win_type[WINTYPE_DROPDOWN_MENU] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_DROPDOWN_MENU", False);
+  win_type[WINTYPE_POPUP_MENU] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_POPUP_MENU", False);
+  win_type[WINTYPE_TOOLTIP] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_TOOLTIP", False);
+  win_type[WINTYPE_NOTIFY] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_NOTIFICATION", False);
+  win_type[WINTYPE_COMBO] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_COMBO", False);
+  win_type[WINTYPE_DND] = XInternAtom(dpy,
+    "_NET_WM_WINDOW_TYPE_DND", False);
+}
+
+int
+main(int argc, char **argv) {
+  XEvent ev;
+  Window root_return, parent_return;
+  Window *children;
+  unsigned int nchildren;
+  int i;
+  XRenderPictureAttributes pa;
+  struct pollfd ufd;
+  int composite_major, composite_minor;
+  win *t;
+
+  gettimeofday(&time_start, NULL);
+
+  // Set locale so window names with special characters are interpreted
+  // correctly
+  setlocale (LC_ALL, "");
+
+  get_cfg(argc, argv);
 
   fade_time = get_time_in_milliseconds();
 
diff --git a/compton.h b/compton.h
index c57dd2fd2..88ecbf9fc 100644
--- a/compton.h
+++ b/compton.h
@@ -24,6 +24,8 @@
 // Whether to enable JIT support of libpcre. This may cause problems on PaX
 // kernels.
 #define CONFIG_REGEX_PCRE_JIT 1
+// Whether to enable parsing of configuration files using libconfig
+#define CONFIG_LIBCONFIG 1
 
 // === Includes ===
 
@@ -44,10 +46,16 @@
 #include <locale.h>
 
 #include <fnmatch.h>
+
 #ifdef CONFIG_REGEX_PCRE
 #include <pcre.h>
 #endif
 
+#ifdef CONFIG_LIBCONFIG
+#include <libgen.h>
+#include <libconfig.h>
+#endif
+
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 #include <X11/Xatom.h>
@@ -278,6 +286,34 @@ mstrcpy(const char *src) {
 }
 
 /**
+ * Allocate the space and join two strings.
+ */
+static inline char *
+mstrjoin(const char *src1, const char *src2) {
+  char *str = malloc(sizeof(char) * (strlen(src1) + strlen(src2) + 1));
+
+  strcpy(str, src1);
+  strcat(str, src2);
+
+  return str;
+}
+
+/**
+ * Allocate the space and join two strings;
+ */
+static inline char *
+mstrjoin3(const char *src1, const char *src2, const char *src3) {
+  char *str = malloc(sizeof(char) * (strlen(src1) + strlen(src2)
+        + strlen(src3) + 1));
+
+  strcpy(str, src1);
+  strcat(str, src2);
+  strcat(str, src3);
+
+  return str;
+}
+
+/**
  * Normalize an int value to a specific range.
  *
  * @param i int value to normalize
@@ -285,7 +321,7 @@ mstrcpy(const char *src) {
  * @param max maximum value
  * @return normalized value
  */
-static inline double
+static inline int
 normalize_i_range(int i, int min, int max) {
   if (i > max) return max;
   if (i < min) return min;
@@ -293,6 +329,22 @@ normalize_i_range(int i, int min, int max) {
 }
 
 /**
+ * Select the larger integer of two.
+ */
+static inline int
+max_i(int a, int b) {
+  return (a > b ? a : b);
+}
+
+/**
+ * Select the smaller integer of two.
+ */
+static inline int
+min_i(int a, int b) {
+  return (a > b ? b : a);
+}
+
+/**
  * Normalize a double value to a specific range.
  *
  * @param d double value to normalize
@@ -530,6 +582,12 @@ static Picture
 solid_picture(Display *dpy, Bool argb, double a,
               double r, double g, double b);
 
+static inline bool is_normal_win(const win *w) {
+  return (WINTYPE_NORMAL == w->window_type
+      || WINTYPE_UTILITY == w->window_type
+      || WINTYPE_UNKNOWN == w->window_type);
+}
+
 static bool
 win_match_once(win *w, const wincond *cond);
 
@@ -789,5 +847,16 @@ ev_handle(XEvent *ev);
 static void
 fork_after(void);
 
+#ifdef CONFIG_LIBCONFIG
+static FILE *
+open_config_file(char *cpath, char **path);
+
+static void
+parse_config(char *cpath);
+#endif
+
+static void
+get_cfg(int argc, char *const *argv);
+
 static void
 get_atoms(void);